Macrophages, namely phagocytic cells phagocytize and digest old and deteriorated red blood cells, bacteria and other microscopic particles. They have been found to play an important role in wound repair. They produce substances that stimulate proliferation of fibroblasts, the synthesis of collagen by fibroblasts, and other elements that are necessary for wound healing. For example, it was found that wound repair could be accelerated in old mice by application of the wounds of macrophages derived from peritoneal fluids of young mice (D. Danon, M. A. Kowatch and G. S. Roth, Proc. Natl. Acad. Sci. USA, Vol.86, pp.2018-2020, March 1989).
The present methods of preparing macrophages out of blood monocytes are complicated, expensive, time-consuming and difficult to apply routinely, because they require considerable specialized labour, expensive disposable materials, and specialized laboratory facilities. Moreover, the present techniques involve a significant risk of contamination during preparation and therefore require regular testing to assure the absence of bacterial infection in the resulting suspension of macrophages.